1. Technical Field
The present invention relates to liquid jet heads for ejecting liquid and liquid jet apparatuses equipped with the liquid jet heads.
2. Related Art
Liquid jet apparatuses that eject liquid, such as, for example, functional liquid, ink and the like onto an object, such as, a sheet of paper, a glass substrate, and the like, for forming specified patterns and images thereon have been known. In such apparatuses, pressure chambers are provided in liquid flow paths where liquid, for example, ink flows, and liquid jet heads are used wherein pressures are applied to ink in the pressure chambers by using the electrostriction of piezoelectric elements, whereby the ink is ejected as ink droplets through nozzles located at the very ends of the flow paths.
Because there are needs for thinner liquid jet heads, for example, a structure described in Japanese Laid-open Patent Application JP-A-6-234218 is often used. In this structure, the pressure chamber is disposed in parallel with a plane in which the nozzles are formed. In other words, the pressure chamber is formed with its lengthwise direction being generally orthogonal to the ink ejection direction, whereby a deformation displacement of the vibration plate that composes the pressurizing unit can be made larger, and the thickness of the liquid jet head in a direction perpendicular to the nozzle opening surface where the nozzles are formed can be made thinner.
The liquid jet head described above is provided with a reservoir that is in communication with the pressure chamber and serves as a supply flow path for supplying ink to the pressure chamber. The reservoir is provided for stably replenishing ink in the pressure chamber upon ink ejection.
Accompanied by the trend toward higher image quality of images photographed by digital cameras in recent years, higher resolution prints are demanded. As a solution to such demands, it is well known that minimization of ink droplets may be effective, and it is also effective to increase the level of integration of nozzles to be formed on a liquid jet head. One of the methods to increase the level of integration is to shorten the distance between rows of nozzles.
When a plurality of rows of nozzles are formed on a liquid jet head by using the structure of a liquid jet head described in the aforementioned document, in particular, when there are two rows of nozzles, the distance between the rows of nozzles may be narrowed by placing the pressure chamber outside with respect to the rows of nozzles, for example, as indicated in FIG. 3 of the aforementioned document. However, an ordinary liquid jet apparatus may be used to eject plural kinds of liquids, such as, liquids in multiple colors (for example, yellow, magenta, cyan, black, etc.). Therefore, in order to eject plural kinds of liquids, a liquid jet head having multiple rows of nozzles, for example, four rows of nozzles, eight rows of nozzles, etc., is required. In this case, a pressure chamber is formed between the nozzle rows, such that the distance between adjacent ones of the nozzle rows needs to be made longer than at least the length of the pressure chamber in its lengthwise direction. As a result, the dimension of the pressure chamber in its lengthwise direction would impose a limitation to higher integration of nozzles.
Also, the reservoir is formed at a position that does not overlap the nozzles in a plane as viewed from the nozzle opening surface side, such that, when many nozzle rows, such as, four rows, eight rows or the like, are formed, the distance between adjacent ones of the nozzle rows would become greater according to the forming region of the reservoir.